London Underground urged the drivers' union today to drop its "disgraceful" claim for triple pay for working on Boxing Day which threatens another Tube strike in the capital.

The company said Aslef's leaders had agreed to working arrangements, including higher pay and 6.8 weeks of holiday, on the understanding that this involved working some bank holidays.

The union is planning a 24-hour strike on Boxing Day over a claim for triple pay and a day in lieu.

London Underground (LU) chief operating officer Howard Collins said: "It is disgraceful that Aslef should try to hold Londoners and London Underground to ransom in this way.

"We have a long-standing agreement which all trade unions are signed up to which covers staff working arrangements on bank holidays, and Boxing Day is included in that agreement. To tear that agreement up and seek to disrupt the festive period for Londoners in this way is just cynical.

"We have made every effort to resolve this issue with the Aslef leadership, which has refused to attend talks at Acas to discuss its claim for triple time and a day in lieu for its members."

Colin Stanbridge, chief executive of the London Chamber, said: "The documents published by London Underground clearly show that Aslef are failing to honour an agreement in which they agreed to work bank holidays in return for generous pay and holiday entitlements.

"Boxing Day is a key trading date for the retail and hospitality industries and they will lose millions if Aslef hold London to ransom with their unreasonable pay demands.

"We urge Aslef to honour their agreement with London Underground and think about the harm they will cause thousands of the capital's businesses, many of which are already struggling amidst difficult economic conditions."